| 摘要 |
PROBLEM TO BE SOLVED: To provide an AC-DC arc welding machine by which the calorification of a transistor is suppressed, the increase in a product cost and making a device large are suppressed and a power consumption can be reduced. SOLUTION: In an AC-DC arc welding machine in which a rectifier circuit 7 having a neutral point N on the output side of a welding transformer 6, is provided, the positive output terminal and the negative output terminal of the rectifier circuit 7, are connected to an external output terminal 22 through the transistors 20, 21, and the neutral point N is connected to an external output terminal 10, a switch 40 is provided, the contact 40a of the switch 40 is connected to the transistor 20 in parallel. In the case of outputting a DC, the contact 40a is closed and a DC voltage is outputted to a welding load through the contact 40a. And in the case of outputting an AC, the contact 40a is opened, and the transistors 20, 21 are alternately turned on and off.
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